The present invention relates to an in-line electron gun adapted to be incorporated in a color picture tube.
In general, focusing characteristics of picture tubes are greatly influenced by the diameter of main lenses. That is, the greater the diameter of main lenses, the better the focusing characteristics become. In the in-line electron gun, however, in order to obtain a large diameter of three main lenses, the diameter of three apertures, which are arranged in line, must be increased and consequently the spacing between the beam paths must be also increased. Then it becomes extremely difficult to attain the correct convergence of three electron beams. Furthermore the focusing electrode for forming the main lenses becomes large in size and must be located closer to the neck portion of the glass bulb so that sparks result; that is, resistance to high voltage or the high voltage characteristic is degraded.
As a result, the diameter of the main lenses in an in-line electron gun must be determined by a compromise between focusing, convergence and high voltage characteristics.